THE VISCOELASTICITY AND STABILITY OF CORN OIL-IN-WATER EMULSIONS STABILISED BY WATER SOLUBLE MEAT PROTEINS AND MONO- AND DI-GLYCERIDES

The viscoelastic properties and stability of concentrated corn oil-in-water emulsions stabilised with 2.0% water soluble meat proteins (WSMP) were examined before, and after, partial replacement of WSMP by a blend of mono- and di-glycerides at pH 2.5 - 7.5. Using protein/glycerides mixtures improvements were observed, the level depending on protein/glycerides ratio, mono-/ di-glyceride ratio within the glycerides component, and pH. It is suggested that protein and glycerides associate to form a complex at the critical values of the three variables at which maximum improvement was observed.     

MINOR SURFACE-ACTIVE LIPIDS OF OLIVE OIL AND VISCOELASTICITY OF PROTEIN FILMS AT THE OLIVE OIL-WATER INTERFACE

The influence of the minor surface-active lipids of olive oil on the viscoelastic parameters of bovine serum albumin, sodium caseinate and egg yolk films, formed following adsorption at the olive oil-protein solution interface, was studied. All the parameters substantialy decreased in the case of bovine serum albumin when surface-active lipids were removed from the olive oil while the absence of these components resulted in purely viscous films in the cases of sodium caseinate and egg yolk. Protein film viscoelasticity is probably influenced by olive oil surface-active lipids as a result of their interactions with adsorbed and unfolded protein molecules at the oil-protein solution interface.     

REDUCTION OF THE EXCITED SINGLET STATE OF CHLOROPHYLL AND PHEOPHYTIN AT THE ORGANIC CRYSTAL/AQUEOUS SOLUTION INTERFACE

Abstract— Reduction of the excited singlet state of chlorophyll a , chlorophyll b , and pheophytin a at the surface of perylene, anthracene, and chrysene single crystals has been measured as hole injection current. The dependence of the quantum yield on the standard free-energy difference of the reaction was in accordance with theoretical expectations without correcting for an interaction energy. The maximum quantum yield of only about 10⁻² holes per absorbed photon is ascribed to a very small effective lifetime of the excited singlet state due to concentration quenching of the excited singlet state in the adsorbed dye layer.     

含溴代十六烷吡啶油水体系界面电势振荡的研究

表面活性剂在互不相溶的油水两相间的自发迁移在远离平衡态时能使油水界面各种性质发生周期性变化,对油水界面自发振荡的研究对深入研究生物体系的振荡具有重要意义.本文论述:含溴代十六烷吡啶的油水体系在一定条件下产生穿过液膜的有规则界面电势振荡。     

CELLULAR DELIVERY AND RETENTION OF PHOTOFRIN II: THE EFFECTS OF INTERACTION WITH HUMAN PLASMA PROTEINS

The absorbance and fluorescence spectra of Photofrin II (PII) in the presence of albumin, globulins and lipoproteins from human plasma show that all of these proteins induce a degree of disaggregation of PII material. In addition, there are substantial rearrangements in the distribution of different fractions contained in PII and their binding to the protein. It is shown that these rearrangements have considerable impact on the uptake of PII by cultured cells and the ensuing retention of the drug in the cells. The information on the contribution of fluorescing and non-fluorescing components of PII in the cells was obtained by measuring first the PII fluorescence in suspensions of live cells, followed by chemical extraction of porphyrin material from the same cells. The interaction of PII with low density lipoproteins resulted in markedly lower levels of PII material retained in the cells, compared to protein-free drug exposure. Somewhat better but still inferior PII retention was observed with high density lipoproteins. The samples with very low density lipoproteins showed increased uptake of PII, but the subsequent retention of the drug was low, so that the remaining amount of the drug was not much different than in protein-free samples. The strongest inhibition of PII uptake was seen with albumin, with ensuing retention of PII not significantly different than in protein-free samples. The best retention of PII was observed with globulins, with approx. 25% higher total drug content retained in the cells after long-term clearance relative to protein-free samples.     

CONCERNING THE ORIGIN OF CHARGE AT THE POLYSTYRENE PARTICLE/WATER INTERFACE

The electrophoretic mobility behavior of well-characterized polystyrene latex particles, carrying one type of surface functional endgroups, has been studied as a function of pH. At low pH, the interaction of protons with the functional endgroups increased in the order: Hydroxyl > carboxyl > sulfate; at high pH the order of interaction was reversed; and at intermediate pH no interactions were observed. The particles of the polystyrene latexes in their different forms at the intermediate pH range, dispersed in deionized water, all exhibited the same mobility irrespective of the functional endgroup. The origin of charge in these systems is explained as being the result of either the preferential adsorption of hydroxyl ions or an electron - injection mechanism due to the overlap of local intrinsic molecular - ion states in polystyrene and water. At low concentrations of functional endgroups, the surface properties of the polystyrene latexes are largely dependent upon the hydrophobic nature of the surface.     

RHEOLOGICAL PROPERTIES AND APPLICATIONS OF MESQUITE TREE (PROSOPIS JULIFLORA) GUM 4. RHEOLOGICAL PROPERTIES OF MESQUITE GUM FILMS AT THE OIL-WATER INTERFACE.

The creep compliance-time behaviour of mesquite films adsorbed at a liquid paraffin-water interface ha s been studied as a function of gum concentration, pH and NaCl or CaCl₂ concentration. All the films exhibited viscoelasticity after a short aging time, but at longer aging times only elasticity was found. The lowest values of the rheological parameters were observed at pH 7.0 when pH was varied. Higher values were found at all aging times when NaCl or CaCl₂, was added to the aqueous phase with NaCl exerting a slightly greater effect.     

INTERACTION OP POLYVINYL ALCOHOL WITH LECITHIN AT THE AIR/WATER AND OIL/WATER INTERFACES AND ITS EFFECT ON EMULSION STABILITY

The interaction of polyvinyl alcohol (PVA) with lecithin films at the air/water and xylene/water interfaces was studied at pH 3, the isoelectric point of lecithin. Surface and interfacial tension measurements and electro-phoretie mobility data showed that PVA either replaces the lecithin molecules or becomes coadsorbed with it at the interface. This mixed film has no elasticity and very low interfacial viscosity. However, coalescence rate measurements showed that the emulsion formed by the polymer* lecithin is more stable than that formed with either polymer or lecithin alone. The enhanced stability by the PVA-lecithin mixed film was attributed to steric interaction produced by the adsorbed polymer.     

聚醚型表面活性剂在界面上的分子取向 Ⅱ. 环氧乙烷环氧丙烷共聚多元醇在水面上的表面膜

测定了水面上六种环氧乙烷环氧丙烷共聚多元醇所成表面膜的π-A关系, 其中三种是Plaronie系列ABA型嵌段共聚物(分子量在2×10~3-8×10~3之间), 三种是无规共聚的超商分于(分子量约为2×10~6)。结果表明, 在水相中有46％NaNO_3时, 成膜分子中的聚氧乙烯(EO)链将以一部分留在界面上其众部分伸入水中的方式取向;π越大, 挤入水面下的EO链节越多。聚氧丙烯(PO)链的情形也相似, 但远不如EO链那样易于挤离水面。根据这一模型, 并假定EO链和PO链的行为是相互独立的, 即可将Triton型表面活性剂和聚丙二醇的表面膜的实验结果定量地与Pluronic共聚物和超高分子无规共聚物的表面膜性质联系起来。但当基底水相中无盐时, 成膜分于的EO链极易进入水相, 而且很可能拖带一部分PO链伸进水相; 也就是说, 这时EO链和PO链的行为不再是相互独立的了, 这可以解释实验的结果。     

黄河水体无机固体粒子与镉、铜相互作用的离子交换等温线

报道了本实验室测得的河流等温线是“台阶型”多级离子交换等温线，具体讨论了形成这类新型等温线的原因。     

刚果红与蛋白质相互作用的分光光度研究及其分析应用

在pH4.1的Britton-Robinson缓冲介质中,刚果红与蛋白质在室温下能迅速结合生成红色复合物,其最大吸收波长为488nm,比刚果红本身紫移了32nm。用光度法研究了该结合反应的最佳条件,并在此基础上建立了测定蛋白质的方法。测定蛋白质(BSA)的表观摩尔吸光系数4ε88为2.876×105L.mol-1.cm-1,该法简便、快速、选择性好、灵敏度高,用于人血清样品和含乳饮料中蛋白质的测定,结果与考马斯亮蓝法一致。     

水溶苯胺蓝与蛋白质结合反应的研究及应用

在pH 2.36的Britton-Robinson(B-R)缓冲介质中,水溶苯胺蓝与蛋白质形成显色化合物,其最大吸收波长为688nm,比试剂本身红移88nm,表观摩尔吸光系数达4.25×105L·mol-1·cm-1(牛血清白蛋白)。制定了四种蛋白质的标准工作曲线,用于人血清样品中总蛋白的测定,结果与溴甲酚绿法一致。     

室温下空气与金属铌和钽表面的相互作用

用XPS角分布法研究了铌和钽在室温下与干燥空气的相互作用.结果表明铌和钽表面生成了化学组成分别为Nb_2O_5和Ta_2O_5的氧化物,氧化膜内金属原子和氧原子呈混合状态,从而排除了这种相互作用仅仅是化学吸附的可能性.     

SURFACE PROPERTIES OF THE WATER SOLUBLE FRACTION OF THE WHEAT ENDOSPERM

ABSTRACT

The work on the water soluble fraction shows useful qualities especially since the used material is a waste-water in the wheat starch separation process. One important property is the improvement of baking volume. Another useful property is the surface activity observed in the surface tension studies, which corresponds to a pronounced foam stabilizing effect.     

不对称卟啉化合物的合成及其与氨基酸甲酯的作用

本文合成了含有单取代酰胺基的不对称卟啉及其锌(Ⅱ)络合物Zn(m,2-CNTPP)及Zn(m,3-CNTPP).对三氯甲烷溶液中它们与谷氨酸二甲酯、亮氨酸甲酯以及苯丙氨酸甲酯的作用进行了系统的研究,讨论了卟啉化合物对氨基酸甲酯分子的结合能力、结合方式,以及二者之间的多种存在形式。结果表明,锌卟啉与氨基酸甲酯以1:1的化学计量结合,中心金属锌(Ⅱ)离子和氨基酸甲酯中的氨基配位,卟啉环上的取代基与氨基酸甲酯中的残基可形成氢键、范德华力等弱相互作用。在卟啉和氨基酸甲酯的作用中,氨基与金属离子直接配位,α-碳上的质子靠近卟啉环平面,而酯基中的甲氧基处于远离卟啉环平面的位置。     

THE PHOTOREACTIONS OF 8-METHOXYPSORALEN WITH TRYPTOPHAN AND LENS PROTEINS*

Abstract— We have previously demonstrated that 8-methoxypsoralen (8-MOP) can be found in the lenses of rats injected (i.p.) with this drug, and that its presence can lead to a photosensitized enhancement of lenticular fluorescence. The cutaneous photosensitizing properties of psoralens are thought to be mediated via their excited triplet states, resulting in photoaddition cyclobutane products between pyri-midine bases and 8-MOP. We have now investigated the possibility that similar types of photoadducts could be generated between 8-MOP and the aromatic amino acid residues in lens proteins. Our experiments involved in vitro irradiation (at 360 nm) of aqueous solutions of 0.1 mM 8-MOP plus purified alpha, beta, or gamma crystallins from calf or normal human (under 20 years of age) lenses. UV absorption and fluorescence emission spectra were measured before and after radiation, and aliquots from all experiments were frozen and kept in the dark for subsequent phosphorescence and EPR spectroscopy. Similar experiments were performed with irradiated aqueous solutions of tryptophan or thymine plus 8-MOP. All controls consisted of solutions kept in the dark. NMR spectra demonstrated that the hydrogen atoms at the 3,4 and 4',5' positions of the 8-MOP molecule were lost following irradiation, suggesting that these two sites were involved in the photoproduct formed between tryptophan and 8-MOP. These studies strongly suggest that 8-MOP is capable of forming photoaddition products with tryptophan and with lens proteins as well as DNA in vivo, resulting in its permanent retention within the ocular lens.     

水溶性金属卟啉类过氧化氢酶的催化活性研究

过氧化氢酶与血红蛋白、肌红蛋白一样,统属于血红蛋白质,具有相同的活性部位——铁卟啉,因此金属卟啉作为生物酶模拟的研究有着重要意义和广阔的应用前景。我们曾报道水溶性金属卟啉修饰的阴离子交换树脂类过氧化氢酶的催化活性。本文应用光谱法,通过测量反应(1)生成的醌型染料,进一步研究了Fe—TPPS作为类过氧化氢酶的均相催化活性,得到了较满意的结果。     

2,2联吡啶在水/硝基苯界面对镍离子的电萃取过程研究

金属离子在载体作用下在水/有机相界面的传输机制各异,Koryta、Freiser和Senda等人通过研究分别提出了EC、CE及E机制。本文用循环伏安法(CV)对2.2′-联吡啶在水/硝基苯界面电萃取Ni(Ⅱ)的过程进行了研究,结果表明不同条件下萃取过程分别为C_wEC_0,C_wE和C_0E机制。     

THE ADSORPTION OF POLYSTYRENE SULFONATE AND ETHOXYLATED NON-IONIC SURFACTANTS AT CARBON BLACK-WATER INTERFACE

The adsorption of a series of sodium polystyrene sulfonates with a narrow distribution of molecular weight and ethoxylated non-ionic surfactants ( NP-12, NP-40, NP-100 and C₁₆E₂₀ ) was investigated at carbon black-water interface. Adsorption isotherms of the Langmuir type were obtained for all the samples with negative adsorption free energies. The dependence of maximum of adsorption on molecular weight tor PSSNa was used to obtain information on the macromolecular conformation at the interface; surface geometry effects on adsorption conformation were analyzed using a simplified fractal approach. PSSNa does not adopt a flat conformation at the interface. Non-ionic surfactants ( NP-12, NP-40, NP-100 and C₁₆E₂₀ ) are adsorbed at the interface with the EO chains in a coil conformation.